Friction draft gear



Feb. 20, 1934. Rl R STEVENS 1,947,812

FRICTION DRAFT GEAR Filed Jan. 29, 1930 'I- sl I /6 /2 /3 /7 /4 T553 Ti.5

ATTO EY Patented Feb. 2G, 1934 PATENT OFFICE` FRICTION DRAFT GEAR Roy R.Stevens, Forest Hills, Pa., assigncr'to The Westinghouse Air BrakeCompany, Wilmerding, Pa., a corporation of Pennsylvania ApplicationJanuary 29,

Z Claims.

This invention relates to draft gear mechanism of the type in which thecushioning action is performed by successively acting spring andfriction means.

The principal object of the invention is `to provide for the applicationof pressure to the initial spring resistance directly, and to delaycompressive action upon the friction resistance until the springresistance has been availed of Ito the desired extent.

Another object of my invention is to provide an improved draft gearmechanism of the above type having an improved arrangement of thefrictional elements.

Other objects and advantages will appear in the following more detaileddescription of my invention.

In the accompanying drawing; Figure 1 is a plan view, partly in section,of a draft rigging 'i embodying one form of my invention; Fig. 2

is an end elevation of the draft gear mechanism shown in the draftrigging in Fig. 1; Fig..3 is an end elevation of the draft gearmechanism shown in the draft rigging of Fig. 1 and showing the shellcontaining the friction elements partly removed from the main gearhousing; Fig. 4 is a partial plan view, mainly in section, of a draftrigging showing a modified -form of my invention; Fig. is a transversesectional view of the draft gear mechanism shown in Fig. 4 and taken onthe line 5--5; Fig. 6 is a partial sectional View of the draft gearmechanism shown in Figs. 4 and 5 and taken on line 6-6 of Fig. 5; andFig. 7 is a partial plan view,

mainly in section, of a draft rigging showing another modied form of myinvention.

As shown in the drawing, the draft rigging comprises center or draftsills 1-1 of a railway car underframe, and to the inner sides of said "isills are secured the usual front stop lugs 2-2 and rear stop lugs 3 Theinner end of a draw bar 4 is operatively connected to a yoke 5 of wellknown form. Disposed within the yoke 5 is a draft gear mechanismembodying my inr jvention, as well as a follower plate 6, the yoke 5being supported by a detachable saddle plate '7 secured to the draftsills.

The draft gear mechanism shown in Figs. 1, 2 and 3 comprises a chambcredfollower 14, constituting a housing for other elements, having sidewalls 8, tcp and bottom walls 9 and a rear end wall 10 connecting thetop and bottom walls 9. The side walls 8 are preferably omitted adjacentthe rear end wall 10, and the top and `bottom Walls 9 are omitted attheir forward ends.

1930. Serial No. 424,202

A hollow rectangular friction shell 11 is mounted in the forward openend of the mainA gear housing and has sidewalls 16 and top and bottomWalls 17, said shell being open at both ends. A transverse rib or stoplug 12 is provided on the outer face of each side wall 16 of thefriction shell 11 and projects into a transverse groove 13 formed in theinner face of each side wall 8 of the main gear casing, the grooves 13being of greater width than the stop lug 12 for permitting relativemovement between the friction shell and main gear housing.

A pair of longitudinal oppositely disposedV wear plates 18 and 19 arefitted against the sidev walls of the friction shell and are anchored inits top and bottom walls 17 by the engagement of lugs 45 on said plateswith corresponding grooves 46 in the top and bottom walls. The wearplates 18 and 19 are thus adapted to be maintained in stationaryengagement with the inner faces of the side walls 16 and are'providedwith wedging friction faces 20 and 21,V respectively, which are adaptedto engage outer.; faces of a pair of oppositely disposed movablefriction shoes 22 and 23. The friction shoe 22 has a friction face 24engaging a corresponding friction face of a Wedge block 25, while thefric-V tion shoe 23 has an oppcsitely facing frictionV face 40 engaginga corresponding friction face of a Wedge block 26. Y

The wedge blocks 25 and 26 are disposed on the opposite sides of athrust-like member 27 and have parallel friction faces 28 and 29,respectively, engaging the opposite parallel sides of said member.

The member 27 is T-shaped and is provided at its forward end with across head 30, the.

rality of nests of springs, comprising outer'.

springs 33 and springs 34 contained within the springs 33. At one end,the springs 33 and 34 engage the rear end wall 10 of the gear housing.The forward ends of the springs 33 engage a spring plate and hold saidplate in engagement with the rear end of the member 27. The Y forwardends of the inner springs 34 extend through apertures in the springplate k35 and sliy engage another spring plate 36 spaced from the springplate 35 and having a central opening through which the member 27extends, the front face of the spring plate 36 engaging the rear facesof the two wedge blocks and 26.

A key 37 is fixed in the top and bottom walls 17 of the friction shell11 and extends through a slot 38 formed in the member 27, therebylimiting outward movement of said member and thus holding the frictionelements assembled.

To assemble the draft gear mechanism, the nests of springs 33 and 34 andthe spring fcllower are placed in position in the main gear housingthrough the openings in side walls 3. The spring follower 36 is insertedthrough the open forward end of the main gear housing. The stop lugs 12on the friction shell 11 are then started in the 'grooves 13 in the maingear casing, and the friction shell is pushed into the position shown inthe drawing, the method of insertion of the friction shell into the maingear casing being most clearly shown in Fig. 3 of the drawing, in whichthe friction shell is partly removed from the casing.

The wear plates 13 and 19 are then assembled with the lug on each sideof said plates inserted into the corresponding groove 46 in the top andbottom walls 17 of the friction The wedge blocks 25 and 26, frictionshoes 22 and 23, and member 27 are then assembled in the friction shellin the relation shown in Fig. 1 of the drawing, after which pressure isapplied to head 30 of the member 27 which compresses springs 33 and 34and moves the friction elements to the position shown in the drawing inwhich the key 37 is inserted through the top and bottom walls 17 of thefriction shell l1 and slot 33 in the member 27.

In operation, during compression of the draft gear mechanism, thefollower plate 6 and main gear casing are moved relatively toward eachother. The pressure applied to the head portion 30 of the member 27moves it and the friction shell, containing the friction elements,

forward in the main gear housing, thereby compressing springs 33 and 34.During this action the friction elements advance as a unit, that is,without relative movement, and consequently offer no resistance, suchadvance being opposed only by the springs 34. When the lugs 12 on thefriction shell 11 engage the rearward face of the transverse grooves 13in the side walls 8 of the main gear housing, relative movement of thefriction shell and main gear housing is stopped, after which thefriction elements contained in the friction shell 11 are operated tobuild up a greater resistance to compression than is provided by springs33 and 34.

After the relative movement of the friction shell and main gear housingis stopped, the pressure acting through the head 30 of member 27 forcesthe friction shoes 22 and 23 inwardly and against the wedge faces of thewear plates -18 and 19 and against the wedge faces of the wedge blocks25 and 26. Due to the inclination of the wedge surfaces on the wearplates 18 and 19, the friction shoes 22 and 23 are also moved inwardlyor transversely of the friction -shell, resistance being effective atthe wedging faces 20 and 21 of the wear plates 18 and 19 and faces 31and 32 of the friction shoes. Such movement of the friction shoesdisplaces the wedge blocks 25 and 26 rearwardly at a rate exceeding therelative movement of the member 27 and main gear casing, frictionalresistance to movement thereby being effective on friction surfaces 28and 29 which engage the parallel faces of the member 27 and on frictionsurfaces 24 and 40 of the friction shoes. During this movement, thesprings 33 are further compressed by the member 27 and the springs 34are compressed by the movement of the wedge blocks 25 and 26. Thisaction continues until the follower plate 6 engages the forward face ofthe side walls 3 of the main gear housing at which time the draft gearmechanism becomes a solid unit.

During release of the mechanism, upon the actuating force being reduced,the expansive action of the springs 33 and 34 effect restoration of thefriction shell 11 to its normal position. Springs 33 force the member 27outwardly until limited by hey 37 in slot 38, and springs 34 acting onwedge blocks 25 and 26 move said blocks and the friction shoes 22 and 23outwardly until movement thereof is limited by the head 30 on member 27.

t will be noted that the movement of the member 27 during the latterportion of the compression and release of the draft gear mechanism isresisted by the frictional engagement of the wedge blocks 25 and 26 onopposite parallel faces of said member. Although this is the preferredconstruction of my improved draft gear mechanism, it may be desirableunder certain conditions to have the member 27 movable freely relativeto the friction elements, such a modified construction being shown inFigs. 4, 5, and 6 of the drawing. Another modification shown in Figs. 4,5, and 6 relates to the means for obtaining preliminary springresistance followed by frictional resistance in a draft gear of the typecontained within a single housing.

In the following description of the modified forms of my invention, theparts which are like the parts shown in the preferred form will beindicated by like reference characters.

The draft gear mechanism shown in Figs. 4, 5, and 6 of the drawing,comprises a hollow rectangular housing having side walls 75, top andbottom walls 47 and a rear end wall (not shown), the forward end of saidcasing being open and the side walls being omitted adjacent the rear endwall.

Within the housing are oppositely disposed a pair of wear plates 13 and19, engaging the side walls and anchored in the top and bottom walls 47by the engagement of lugs 45, on each of said plates, in a transversegroove 48 formed in both the top and bottom walls. A spacer 49, having acentral rectangular longitudinal opening 51 therethrough and atransverse rib 50 on each end, is disposed within the gear housing, theribs 50 projecting into transverse grooves 43 in the top and bottomwalls thereof. Fricticnally engaging the two opposite sides of 135 thespacer 56 are wedge blocks 25 and 26, and interposed between said wedgeblocks and the wear plates 13 and 19 are friction shoes 52 and 53,respectively, each of said friction shoes having a toe 54 extendinglaterally outwardly overlapping the rearward face of the adjacent wearplate. Engaging the rearward end of the wedge blocks 25 and 26 is aspring plate 36 subject to the pressure of springs 34.

A thrust member 27 is freely movable through the opeining 51 in thespacer 49 and at the rearward end engages a spring plate 35, which issubject to the pressure of springs 33.

To assemble this draft gear mechanism, the springs 33 and 34 andfollower plate 35 are in- 15o serted through the open side walls ofthehousing and then positioned as shown inthe drawing. The follower 36 isinserted through the open forward end of the housing. The wear plates 18and 19 are turned diagonal to the verical transverse axis of thehousing, then inserted through the open end of the housing until lugs 45line up with the transverse grooves 48. The wear plates are then turnedparallel to the vertical transverse axis of the housing and positionedas shown in the drawing. in a like manner, the spacer i9 is alsoassembled in the housing. Next the wedge blocks 25 and 26 are positionedas shown, in engagement with the spring plate 36. The friction shoe 52is inserted between wear plate 18 and wedge block 25, and the frictionshoe 53 is inserted between wear plate 19 and wedge block. 26. Themember 27 is inserted through opening 51 in spacer 49 and pressure isthen applied to the head 30 of member 27, which acts through springfollower 35 to coinpress springs 33 and at the same time engages andshifts the friction shoes 52 and 53 rearwardly until the toe 54 on eachof said shoes passes the rearward end of the wear plates 18 and 19. Thekey 37 is then inserted through the housing and member 27 after whichthe pressure is removed from the member 27. Thereupon the spring 33moves the member 27 to the position shown in the drawing, in which thehead 30 is out of engagement with the friction shoes 52 and 53. Whenpressure is removed from the thrust member, the pressure of springs 34shifts the wedge blocks and friction shoes to the position shown in thedrawing in which the toe 54 on each of said shoes engages the rearwardend of the corresponding wear plate.

The operation of this modified form of draft gear mechanism issubstantially the same as the operation of the preferred form shown inFigs. 1, 2, and 3 of the drawing and hereinbefore described, except itwill be noted'that the member 27 and springs 33 only are in actionduring the preliminary compression stroke, i. e., before the frictionelements are operated, and are entirely free of frictional resistancefrom the friction elements, since t .e thrust member eX- tends freelythrough the opening 51 in spacer 49 to engage the spring follower.During compression, when the purely spring action is completed, the head30 of the thrust member, engages the forward faces of the friction shoes52 and 53 and operates the friction elements. The friction elementsoperate in the same manner as those shown and described in Figs. 1, 2,and 3 of the drawing, except that the friction faces 28V and 29 of thewedge blocks 25 and 26, respectively, operate against correspondingfaces of the stationary spacer 49 instead of against a relativelymovable member 27 as hereinbefore described.

1n Fig. 7 is shown another modified form of my invention which issubstantially the same as that shown 1, 2 and 3 and hereinbeforedescribed, except for the wedging system.

The draft gear mechanism shown Yin Fig. 7 comprises a main gear housing14, a friction shell l1 removably inserted in the forward end of themain gear housing and relatively mov lable thereto. The main gearhousing `has top and bottom walls 9, side walls 8 and a rear end wall(not shown), the side walls S being omitted adjacer. the rear wall, andthe top and bottom walls are omitted at the forward ends. Contained inthe friction shell are removable weer plates i8 and 19 anchored to thetop and bottom walls 9 of the main shell by lugs 45 eX- Vtending intocorresponding grooves in the shell wall. Frictionally engaging said wearplates are a pair of spaced friction slices 56 and 57 and interposedbetween said friction shoes and having frictional engagement therewith,is a thrust member 53.

The member 58 extends through the friction shell and a spring follower36, and engages a spring follower 35 between which and the rear end wallof the main gear casing springs 33 are interposed. The spring follower36 engages the rearward ends of the friction shoes 56 and 57, and isengaged by one end of springs 34, the opposite ends of which also engagethe rear end wall of the main gear housing.

This draft gear mechanism is assembled in the same manner as the draftgear mechanism shown in Figs. 1, 2 and 3 of the drawing and hereinbeforedescribed.

in operation, under compression, the follower plate 6 and main gearhousing 14 are moved relatively toward each other. The resistance tomovement of the friction elements Within the friction shell is greaterthan the compressive force of the springs 34, so that under compresion,the friction shell is initially moved as a unit relative to the maingear housing, thereby compressing the springs Se. When the lugs 12 105on the friction shell engage the rearward faces of grooves 13 in themain gear housing, relative movement between said shell and housing isstopped. Further compression of the gear mechanism then causes the wedgefaces 60 and 110 61 on the member 53 to displace the friction shoes 56and 57 rearwardly along the wedging faces 21 and 2G of the wear plates19 and 18, which effects a lateral inward movement of said frictionshoes.

During release of the mechanism upon a reduction in the actuating force,springs 33 and 34 expand and restore the thrust member and frictionshell 11 to their normal positions. Springs 35 acting through springfollower S5 120 shift the member 58 forwardly, which permits springs 34acting through spring follower 36 to shift and return the friction shoes56 and 57 to their normal positions.

While illustrative embodiments of the inven- 125 tion have beendescribed in detail, it is not my intention to limit its scope to suchembodiments or otherwise than by the terms of the appended claims.

Having now described my invention, what I 130 claim as new and desire tosecure by Letters Patent, is:

1. In a draft gear mechanism, the combination with a casing, of amovable compression member extending into said casingY and havingfriction surfaces at right angles to the longitudinal center line of thecasing, a movable wedge bloeit on each side of said compression member,a movable friction shoe on each side of said compression member andadapted to have l wedginCr engagement with each of said wedge blocks andfrictional engagement with the friction surfaces on said compressionmember, a stationary friction plate anchored to each of two oppositesides of said casing and engaging #ai said friction shoes, a spring foropposing the movement of said compression member, and another spring foropposing the movement of said wedge blocks and friction shoes.

2. In a draft gear, in combination, a cham- 55 bered follower, alongitudinally apertured friction block within the open end of thefollower and anchored thereto against longitudinal movement and havinglateral friction faces, cooperating Wedge elements interposed betweenand frictionally engaging the side walls of the follower and of thefriction block, a, thrust member engageable with the outer end of one ofthe wedge elements of each pair and having a stem projecting through thefriction block, and independent spring means opposing the advance of theWedge elements and of the thrust member.

ROY R. STEVENS.

